Blackjack · Explanation
How blackjack works
Blackjack is played with a 52-card deck. You and the dealer each get two cards; your goal is to finish closer to 21 than the dealer without going over. Face cards count 10, aces count 1 or 11.
On your turn you can hit (take another card), stand (keep your total), double (double your bet, take exactly one more card), split (if your two cards match, play them as two separate hands), or surrender (give up half your bet, where allowed). A two-card 21 — blackjack — pays 3:2 and beats everything except another blackjack.
The dealer plays by fixed rules: hit until 17, then stand (some tables make the dealer hit soft 17). If the dealer busts, every remaining player hand wins.
Using this site
Basic Strategy →
Color-coded charts showing the mathematically optimal play for every hand total vs every dealer upcard, across thousands of casino rulesets. Adjust the rules in the panel above and watch the chart update. Turn on “Show EV” to see the exact expected value of each cell.
Hand Calculator →
Enter any two player cards and the dealer upcard to get the exact expected value of every legal action — hit, stand, double, split, surrender — with win/push/loss probabilities for each. Useful for checking a specific hand rather than reading the full chart.
Dealer Outcomes →
Exact probabilities for what the dealer ends up with (17 through 21, bust, or blackjack) for each upcard, under S17 and H17 rules, before and after the blackjack peek.
All numbers are computed by exact dynamic programming over an infinite-deck model — not Monte Carlo simulation. For education only, not gambling advice.